Histopathology of the infected walnut roots (Juglans regia L.) with root-knot nematode Meloidogyne incognita showed that roots were completely destroyed because of infestation during a study in Hazara Division, KP, Pakistan. Meloidogyne species are potential pest of associated plants and trees. Damaged roots taken from infested host trees were fixed, sectioned and stained for histopathological study. Results showed that second stage juveniles (J2s) established themselves in the roots very successfully and resulted in the formation of giant cells. Cells with dense cytoplasm and multinuclei were observed. Feeding sites were developed and necrosis of root along with hypertrophy was seen. Cortex was completely destroyed which is a major component of ground tissue. Transverse section of the root cells showed presence of female sections and egg masses. Statistical analysis showed that Meloidogyne incognita had mean value 24±1.8 S.D value.

Key Words: Meloidogyne incognita, Giant cells, Hypertrophy, Cortex, Egg masses.